Lower limb pain in a preadolescent population: prognosis and risk factors for chronicity--a prospective 1- and 4-year follow-up study.

OBJECTIVE: To determine the short-term and long-term prognosis of preadolescent lower limb pain and to assess factors that contribute to pain persistence at 1-year follow-up and pain recurrence at 4-year follow-up.
METHODS: A 1- and 4-year follow-up was conducted of a population-based 10- and 12-year old cohort of schoolchildren with lower limb pain at baseline.
RESULTS: Of the baseline students with lower limb pain, 32% reported pain persistence at 1-year follow-up and 31% reported pain recurrence at 4-year follow-up. Vigorous exercise was the only statistically significant predictor of lower limb pain persistence at 1-year follow-up (odds ratio [OR]: 2.43; 95% confidence interval [CI]: 1.16-5.05), whereas at 4-year follow-up (at adolescence), hypermobility was predictive of pain recurrence (OR: 2.93; 95% CI: 1.13-7.70). Traumatic lower extremity pain had a 50% lower risk for pain recurrence compared with nontraumatic pain (OR: 0.48; 95% CI: 0.19-0.92).
CONCLUSION: Trauma-induced lower extremity pain in preadolescents has a favorable long-term natural course. Children's involvement in vigorous exercise predicts short-term outcome of lower limb pain, whereas hypermobile children have a worse long-term prognosis.